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Expansion tank sizing

Brad White
Brad White Member Posts: 2,398
a second Amtrol 30 according to my selection spreadsheet. At 145 gallons, 50 to 180 degrees range, 13 psig cold fill pressure and 30 psig maximum pressure, I came up with an acceptance volume requirement of just under four gallons.

The Amtrol 30 has an acceptance volume of 2.5 gallons. Two are less money than a single 60, besides, you already have one. Get another to keep it company.
"If you do not know the answer, say, "I do not know the answer", and you will be correct!"

-Ernie White, my Dad


  • Thermostat Man
    Thermostat Man Member Posts: 2
    expansion tank sizing

    I am a homeowner who believes my extrol 30 is too small. I have a converted two pipe steam powered by a Dunkirk 240k. Two years ago I noticed pressure was building to 30lbs and the release valve would activate. I called a local professional and they determined the diaphragm of my then extrol 30 had failed and was replaced with same size. When the technician fired the system he commented that the pressure in the low 20s seemed a little high. My house is two stories and the pressure gauge reads 13lbs when the system is cold. At water temp of 150 it registers 23lbs. It has not popped off this heating season. I had to drain the system to remove a radiator to replace a kitchen floor. I measured the volume of the system to be 145 gallons when I took it down. It appears to me that I need the extra capacity of the extrol 60. What is the verdict?
  • Doug_39
    Doug_39 Member Posts: 12
    Thanks to the help of some of the pros here.....

    ....our pressure problem appears to have been resolved. We were running previous peaks at 30 psi and more, but now, things are much better, with most peaks at or below 20-25 psi. We ended up replacing our Amtrol Extrol 30 with a Watts ET60. Dimensionally, the Watts isn't all that much bigger than the Amtrol, but, the Watts has a larger expansion capacity. Since space limitations were an issue, we upsized, rather than purchase a 2nd AE30. I gave our old one to the installer who helped us out, otherwise I could have passed it on. Many thanks again to the pros for taking the time to read and respond.
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